Bioelectric Characterization of Senescing Human Keratinocytes

Aging, a ubiquitous process that affects almost all multicellular organisms, is accompanied by the accumulation of senescent cells, leading to a decline of morphology and function. The ‘loss of morphostatic information’ theory posits that aging occurs due to gradual breakdown of order initially established during embryo development. Spatial differences in cellular resting potential have many roles in organizing cell activity into complex anatomical structures during embryogenesis and regeneration. Thus, while bioelectric patterns are a good candidate for the information that degrades during aging, long-term changes in bioelectrical state in adult cells are not well-understood. Here, we sought to characterize the temporal and spatial bioelectric dynamics of human epidermal keratinocytes undergoing replicative senescence. We stained keratinocytes of varying ages using the voltage sensitive dye – BeRST – and characterized p16 expression levels and senescence associated β-galactosidase activity. Our results revealed senescence-associated membrane depolarization – consistent change of bioelectrical potential over the lifespan of cells. Moreover, we found increased levels of Vmem heterogeneity, reduced cellular responsiveness to hyperpolarizing treatments, diminished resilience (ability to quickly and effectively achieve equilibrium post-perturbation), and degradation of bioelectricspatial organization. These results reveal a breakdown of bioelectric patterning and regulation with senescence consistent with the loss of morphostatic information theory of aging.